It has already become known that specific phenylsulphonyl-imidazoles and phenylsulphonyl-benzimidazoles have fungicidal properties (cf. EP-A 0 238 824 and WO 97-06 171). Thus, 1-(2-methyl-5-nitro-phenylsulphonyl)-benzotriazole, 2-methyl-1-(2-methyl-5-nitro-phenylsulphonyl)-imidazole and 1-(2-methyl-5-nitro-phenylsulphonyl)-2-chloro-6,6-difluoro-[,1,3]-dioxolo- [4,5-f]-benzimidazole can be used for controlling fungi. The activity of these substances is good but is unsatisfactory in some cases at low application rates.